Further to Jody's comment, CityGML is an application profile (also
referred to as a community schema), which provides more details about a
specific domain than GML. I describe it in more detail here:
http://cameronshorter.blogspot.com/2008/10/community-schemas-making-sense-out-of.html
On 04/08/10 23:42, Jody Garnett wrote:
The idea of geometry is the same for each system from national GIS datasets; to
small datasets used to track each fire hydrant for a city. You are correct you
need a bit of information about each data set (units, projection, when the data
when collected and what accuracy).
You may consider looking at CityGML which is intended to be an interchange
format for city scale information; all there demos seem to be visual
fly-through etc...
As for having information about lanes and so forth; that is real up to your
data provider; often that information is not available for free. Sometimes you
can source it from councils or local governments; but be aware that it may not
be set up for navigation (indeed it may of been collected for another purpose
such as maintenance or council asset management etc...). So the good news is
they may be recording the lines of paint on the road; the bad news is they may
not be recording what those lines mean in terms of where cars can turn.
My best advice would be to approach a local council and offer to use their city
as a pilot for your program and see if you can arrange data access in that
manner.
Jody
On 04/08/2010, at 10:07 AM, berryman wrote:
Hello,
I am hope to use GIS for a traffic analysis program that I am involved with.
After having looked at a couple weeks worth of GIS resources, I still feel
like I haven't found what I'm looking for and it's time to get some human
input.
The main source of my frustration is that all of the standard data formats
seem to be too general for my purpose. Common formats provide the ability
to encode points, lines, polylines, and polygons (where the locations are
unitless). But I need the ability to encode the geographic location (e.g.
lat/long, NAD83) of high-level constructs. For instance, I'm not just
interested in the location of streets, I'm interested in the location of
each lane. I also need to know how street topology and traffic direction so
that I can make path planning determinations. Finally, it would even be
ideal if I could encode the location of traffic signals, stop signs,
bus-only lanes, etc.
I know that these types of encoding must exist somewhere , because my Garmin
GPS understands the rules of the streets and can anticipate things coming
up. For instance, it might tell me "stay in the right lane." Are there
standard data formats for encoding this information? Or is the ability to
encode this a non-public extension of some more generic standard? If so,
then how do I go about extending some other standard for my application?
Thanks all!
--
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Cameron Shorter
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Think Globally, Fix Locally
Geospatial Solutions enhanced with Open Standards and Open Source
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